The three suicide bombers who carried out Tuesday's attack on Istanbul's main airport that killed 42 people were of Russian, Uzbek and Kyrgyz nationality, a Turkish official said on Thursday.

The police detained 13 people, three of them foreigners, in simultaneous raids across 16 places in Istanbul in connection with the suicide bombings at Istanbul's main airport, a Turkish official said on Thursday.

The three bombers opened fire to create panic outside before two of them got inside the terminal building and blew themselves up. The third detonated his explosives at the entrance. A further 239 people were wounded.

The official gave no further details beyond confirming the attackers' nationalities and declined to be named because details of the investigation had not been released. Investigators had been struggling to identify the bombers from their limited remains, officials said earlier.

"A medical team is working around the clock to conclude the identification process," one of the officials said.

The pro-government Yeni Safak newspaper said the Russian bomber was from Dagestan, which borders Chechnya, where Moscow has led two wars against separatists and religious militants since the Soviet Union collapsed in 1991.

The Kyrgyz security service declined to comment, while the Uzbek security service could not immediately be reached.

Turkish Interior Minister Efkan Ala told Parliament on Thursday that the evidence gathered so far pointed to Islamic State responsibility. The attack has not yet been claimed by any terrorist group.

Turkey declared a day of national mourning after the deadliest and highest-profile attack in a string of killings and bombings that have gripped the country this year.

Foreign heads of state have expressed their solidarity with Turkey and presented their condolences, but for Turkish Foreign Minister Mevlut Cavusoglu, it is "not enough" to show solidarity in response to terrorist attacks.

Cavusoglu made the comments at a news conference in Brussels to announce the "opening" of Chapter 33 in Turkey's European Union accession process, which covers budget policy.

Cavusoglu also said he expected the European Union to meet its commitments regarding the visa liberalisation.